Scroll Compressor

ABSTRACT

The invention provides a scroll compressor in which a movable scroll is supported from a back face with a plurality of thrust plates without being inclined. 
     The scroll compressor of the invention has a compression unit including a movable scroll made up by forming a vortical wrap in an end wall and a similar fixed scroll, and being capable of carrying out compression along with an orbiting movement of the movable scroll with the wraps of the scrolls engaged with each other; a movable-scroll receiving support surface formed on a back-face side of the end wall of the movable scroll and including a flat face opposite to the back face of the end wall; and a plurality of thrust plates that are scattered in the support surface along a circumferential direction of the movable scroll, slidably supports the back face of the end wall of the movable scroll, and receives a thrust load from the movable scroll. The thrust plates are fixed onto the flat face of the support surface so as to be supported with the flat face by using the flat face as reference.

TECHNICAL FIELD

The present invention relates to a scroll compressor in which a fixedscroll and a movable scroll are combined together to carry outcompression.

BACKGROUND ART

Scroll compressors are used in automobile air-conditioning systems, homeair-conditioners, refrigerators, etc. Many of these scroll compressorsuse a compression unit in which a vortical wrap of a fixed scroll andthat of a movable scroll are engaged with each other.

In the compression unit, the orbiting movement of the movable scrollgradually reduces the capacity of a crescent-shaped compression chamberthat is formed between the vortical wrap of the fixed scroll and that ofthe movable scroll. This action of the compression chamber is used tocompress a to-be-compressed fluid such as a refrigerant.

During compression, the movable scroll is applied with load in an axialdirection, namely in a thrust direction, as a reaction force of thecompression. In other words, the load acts to separate the movablescroll away from the fixed scroll. In order to suppress this action thatdeteriorates the compression performance, the scroll compressor isprovided with a movable-scroll receiving support surface in the backface of an end wall supporting the wrap of the movable scroll, and alsoprovided with a thrust receiving structure for receiving a thrust loadin the movable-scroll receiving support surface.

The thrust receiving structure is required to be designed inconsideration of downsizing of the compressor.

In late years, as shown in Unexamined Patent Publication No.2005-291151, it has been suggested to provide a thrust receivingstructure with a plurality of thrust plates made up of small disc-likeparts in the movable-scroll receiving support surface to be arranged ina circumferential direction of the movable scroll by using an embeddingconstruction. Recessed areas are formed in a flat section of themovable-scroll receiving support surface, which faces the end wall ofthe movable scroll, along the circumferential direction of the movablescroll. The thrust plates are interfitted in their respective recessedareas so that the upper faces of the thrust plates slightly project fromthe openings of the recessed areas. In other words, the thrust platessupported with the bottom faces of the recessed areas each have astructure for receiving the end wall of the movable scroll. As thisstructure uses a plurality of disc-like thin parts, it has the advantagethat the thrust receiving structure itself is compact.

Preferably, in order to maintain the compression performance, themovable scroll orbits around the axis of the fixed scroll while keepinga parallel attitude.

In the structure disclosed in Unexamined Patent Publication No.2005-291151, however, the thrust plates are supported with the bottomfaces of the recessed areas, so that the movable scroll is inevitablyaffected by variation generated during the machining of the recessedareas.

More specifically, the recessed areas are formed in the respectivesections of the movable-scroll receiving support surface by machining.However, the machining is prone to generate variation in a depthdirection. The thrust plates are the parts arranged along thecircumferential direction of the movable scroll and supporting themovable scroll from the back face of the movable scroll. Thedepth-directional variation in the recessed areas emerges as aninclination of the movable scroll. This means that the movable scroll isengaged with the fixed scroll in an inclined position due to the thrustplates.

This inclination of the movable scroll affects a compression stroke thatis carried out between the fixed and movable scrolls and is liable tocause a deterioration in compression performance.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a scroll compressorin which a movable scroll is supported from a back face with a pluralityof thrust plates without being inclined.

The scroll compressor according to the invention has a compression unitincluding a movable scroll made up by forming a vortical wrap in an endwall and a similar fixed scroll, and being capable of carrying outcompression along with an orbiting movement of the movable scroll withthe wraps of the scrolls engaged with each other; a movable-scrollreceiving support surface formed on a back-face side of the end wall ofthe movable scroll and including a flat face opposite to the back faceof the end wall; and a plurality of thrust plates that are scattered inthe support surface along a circumferential direction of the movablescroll, slidably supports the back face of the end wall of the movablescroll, and receives a thrust load from the movable scroll. The thrustplates are fixed onto the flat face of the support surface so as to besupported with the flat face by using the flat face as reference.

Since the invention has a structure in which the thrust plates aresupported with the flat face of the scroll-receiving support surfacethat can be maintained with high accuracy, the movable scroll can besupported with the thrust plates from the back face without beingunnecessarily inclined.

It is therefore possible to suppress a reduction in compressionperformance, which is caused by inclination of the movable scroll, andthen to improve the compression performance of the scroll compressor.

Preferably, according to the scroll compressor of the invention, each ofthe thrust plates has a projection protruding toward the supportsurface, and the support surface has a hole that opens toward thecorresponding thrust plate. Each of the thrust plates is fixed onto thesupport surface by interfitting the corresponding projection into thecorresponding hole.

With this scroll compressor, the thrust plates are firmly fixed onto theflat face of a scroll-receiving support surface without inclining thethrust plates with a simple structure.

Preferably, according to the scroll compressor of the invention, thesupport surface has a projection protruding toward the correspondingthrust plate, and each of the thrust plates has a hole that opens towardthe support surface. Each of the thrust plates is fixed onto the supportsurface by interfitting the corresponding projection into thecorresponding hole.

With this scroll compressor, the thrust plates are firmly fixed onto theflat face of the scroll-receiving support surface without inclining thethrust plates with a simple structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a normal sectional view of a scroll compressor according to afirst embodiment of the invention;

FIG. 2 is a sectional view taken along line II-II of FIG. 1;

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is an exploded perspective view showing a fixing structure of athrust plate;

FIG. 5 is a sectional view showing a substantial part of a secondembodiment of the invention; and

FIG. 6 is an exploded perspective view showing a fixing structure of athrust plate according to the second embodiment.

BEST MODE OF CARRYING OUT THE INVENTION

The invention will be described with reference to a first embodimentshown in FIGS. 1 to 4.

FIG. 1 is a normal sectional view of a scroll compressor, or forexample, an electric scroll compressor for vehicle air-conditioning.FIG. 2 is a sectional side view taken along line II-II of FIG. 1. FIG. 3is a partially sectional view taken along line of FIG. 2. FIG. 4 shows afixing structure of a thrust plate.

In FIG. 1, reference mark 1 represents a housing of the scrollcompressor. The housing 1 is constructed by serially connecting acompression-unit casing 1 a having a shape of a cylinder with a bottomto a similar electric-unit casing 1 b with a cylindrical middle casing 1c disposed therebetween.

A compression unit 5 is installed in the compression-unit casing 1 a.The compression unit 5 has a structure in which a fixed scroll 3disposed on the bottom side of the casing 1 a is engaged with a movablescroll 4 disposed on the opening side. More specifically, the fixedscroll 3 and the movable scroll 4 each have a structure in which avortical wrap 8 is disposed, for example, in a circular end wall 7. Inthe center of the back face of the end wall 7 of the movable scroll 4,there is a cylindrical boss 11 in which an eccentric bush 10 isrotatably fitted. A wrap 8 of the fixed scroll 3 and a wrap 8 of themovable scroll 4 are engaged with each other. A crescent-shapedcompression chamber 12 having capacity varied along with an orbitingmovement of the movable scroll 4 is formed between the wraps 8.

In the middle casing 1 c, there is formed a cylindrical protrudingportion that protrudes close to the end wall 7 of the movable scroll 4.The protruding portion serves as a movable-scroll receiving supportsurface 13 (hereinafter, referred to as a support surface 13) thatreceives the movable scroll 4. The support surface 13 has a tip end facethat is formed of a ring-like flat face 13 a parallel with the end walls7 of the fixed and movable scrolls 3 and 4. Needless to say, the flatface 13 a is situated closely opposite to a back face 7 a of the endwall 7.

An electric unit 17 formed by interlocking a rotor 15 and a stator 16together is installed in the electric-unit casing 1 b to be located onthe opening side. On the bottom side, there is disposed an inverter unit18 for controlling the electric unit. The rotor 15 has a shaft 15 aincluding both ends rotatably supported with bearings 19 and 20 that areset in the electric-unit casing 1 b and the middle casing 1 c. In theshaft 15, an eccentric pin 21 is set in an eccentric position of a shaftend of a shaft 10 a supported with the middle casing 1 c.

The eccentric pin 21 is inserted in an eccentric aperture located in aneccentric position of the eccentric bush 10 of the movable scroll 4. Inresult, when the rotation of the rotor 15 is transmitted through theeccentric bush 10 to the movable scroll 4, the movable scroll 4 orbitsaround an axis of the fixed scroll 3 to vary the capacity of thecrescent-shaped compression chamber 12, to thereby compress ato-be-compressed fluid such as refrigerant. The movable scroll 4 doesnot rotate on its axis and is capable of making an orbiting movementonly, by using four pin-type rotation-suppressing devices 22 situatedbetween the end wall 7 of the movable scroll and the support surface 13as illustrated in FIGS. 1 and 2.

As illustrated in FIGS. 1 and 2, a plurality of thrust plates 25 arescattered along a circumferential direction of the movable scroll 4between the back face 7 a of the end wall 7 of the movable scroll 4 andthe ring-like flat face 13 a. Each of the thrust plates 25 is made up ofa thin circular member (having, for example, a diameter of about 10 mmand a thickness of about 2 mm).

The fixing of the thrust plate 25 uses a structure that supports theentire thrust plate 25 by using the flat face 13 a of the supportsurface 13 as reference plane, in which accuracy can be easily obtained.In this structure, a projection such as a short-columnar projection 28is formed in either a lower face 25 a (one side face opposite to theflat face 13 a) of the thrust plate 25 or the flat face 13 a (faceopposite to the lower face 25 a) of the support surface 13 as shown inFIGS. 3 and 4. In the other face, there is formed a hole such as a holein which the entire protruding projection 28 is fitted, or morespecifically, an interfitting hole 29.

The above-mentioned structure will be described in detail. For example,as illustrated in FIGS. 3 and 4, the short-columnar projection 28 isintegrally formed in the center (substantially center) of the lower face25 a of the thrust plate 25. A cylindrical interfitting hole 29 with abottom is formed in each point on the flat face 13 a, which coincideswith the corresponding projection 28. The interfitting hole 29 has aninternal diameter size corresponding to an external diameter of theprojection 28 and a depth that is longer than a projection length of theprojection 28. Letter H in FIG. 3 indicates the depth of theinterfitting hole 29. The projection 28 is slidably (rotatably)interfitted in the interfitting hole 29. The entire projection 28protruding from the lower face 25 a is received in the interfitting hole29. The thrust plate 25 is thus positioned at a predetermined point, andthe lower face 25 a of the thrust plate 25 abuts against the flat face13 a. The thrust plate 25 is thus disposed (placed) to be superimposedupon the flat face 13 a. The entire thrust plate 25 is supported withthe flat face 13 a of the support surface 13 from the lower side, and ispositioned at a predetermined position. In short, the thrust plate 25 isfitted onto the flat face 13 a by using the flat face 13 a as reference.

The thrust plate 25 supported with the flat face 13 a supports the endwall 7 of the movable scroll 4 from the back-face side, and receives athrust load applied to the movable scroll 4.

In the scroll compressor, the rotor 15 rotates when the electric unit 17is excited. The rotation is transmitted from the shaft 15 a through theeccentric pin 21 to the movable scroll 4. The movable scroll 4 thenorbits around the axis of the fixed scroll 3, and compresses theto-be-compressed fluid such as refrigerant by varying the capacity ofthe compression chamber 12 located between the wraps 8.

During the compression, the thrust load applied to the movable scroll 4is received by the plurality of thrust plates 25 supporting the end wall7.

At this time point, the thrust plate 25 is superimposed upon the flatface 13 a. In other words, the thrust plate 25 is positioned by usingthe flat face 13 a as reference.

For that reason, even if there generates variation in the depthdirection of the interfitting hole 29 due to the machining of recessedareas, the thrust plate 25 is not affected by the variation. This meansthat the thrust plate 25 is not inclined. This is because the flat face13 a upon which the thrust plate 25 is superimposed is a section inwhich high accuracy is easily obtained.

The movable scroll 4 is properly supported from the thrust plates 25located in any points by using the flat face 13 a as reference. Themovable scroll 4 is therefore not inclined in relation to the fixedscroll 3, and always retains a predetermined attitude, or a proper fixedattitude suitable for compression. Consequently, the movable scroll 4can satisfactorily carry out a desired compression performance incooperation with the fixed scroll 3.

Moreover, the fixing of the thrust plates 25 is carried out withoutdifficulty since the interfitting structure in which the projection 28and the interfitting hole 29 are fitted together is employed.

FIGS. 5 and 6 show a second embodiment of the invention.

According to the present embodiment, unlike the first embodiment, a pinmember 35 is formed as a projection in the flat face 13 a of the supportsurface 13. In the center (substantially center) of the lower face ofthe thrust plate 25, there is formed a through-hole 36 piercing inthickness direction as a hole, whereby the thrust plate 25 issuperimposed upon the flat face 13 a.

To be more concrete, the pin member 35 projects towards the lower faceof the thrust plate 25. The through-hole 36 has an internal diametersize corresponding to an external diameter of the pin member 35. Asillustrated in FIGS. 5 and 6, the pin member 35 is slidably (rotatably)interfitted in the through-hole 36, and the entire pin member 36protruding from the flat face 13 aa is received in the through-hole 36.In result, the thrust plate 25 is positioned at a predetermined point asin the first embodiment, and the entire thrust plate 25 is supportedfrom the lower side by using the flat face 13 a of the support surface13 as reference similarly to the first embodiment.

For that reason, even with the structure opposite to that of the firstembodiment in which the pin member 35 and the through-hole 36 are fittedtogether, it is possible to prevent the inclination of the movablescroll 4 with a simple structure as in the first embodiment.

Members identical to those in the first embodiment are provided withidentical reference marks in FIGS. 5 and 6, and descriptions thereofwill be omitted.

The invention is not limited to the first and second embodiments, andmay be modified in various ways without deviating from the gist of theinvention. For example, the embodiments have a structure in which theprojection and the through-hole are formed in the lower face of thethrust plate, and the hole and the pin member in the flat face. Insteadof such a structure, the invention may have a structure in which thethrust plate is positioned by using the flat face of another supportsurface as reference.

1. A scroll compressor comprising: a compression unit including amovable scroll made up by forming a vortical wrap in an end wall and asimilar fixed scroll, and being capable of carrying out compressionalong with an orbiting movement of the movable scroll with the wraps ofthe scrolls engaged with each other; a movable-scroll receiving supportsurface formed on a back-face side of the end wall of the movable scrolland including a flat face opposite to the back face of the end wall; anda plurality of thrust plates that are scattered in the support surfacealong a circumferential direction of the movable scroll, slidablysupports the back face of the end wall of the movable scroll, andreceives a thrust load from the movable scroll, wherein: the thrustplates are fixed onto the flat face of the support surface so as to besupported with the flat face by using the flat face as reference.
 2. Thescroll compressor according to claim 1, wherein each of the thrustplates has a projection protruding toward the support surface; thesupport surface has a hole that opens toward the corresponding thrustplate; and each of the thrust plates is fixed onto the support surfaceby interfitting the corresponding projection into the correspondinghole.
 3. The scroll compressor according to claim 1, wherein the supportsurface has a projection protruding toward the corresponding thrustplate; each of the thrust plates has a hole that opens toward thesupport surface; and each of the thrust plates is fixed onto the supportsurface by interfitting the corresponding projection into thecorresponding hole.